The present invention relates generally to a mail inserting system and, more particularly, to an envelope transport module to be used in the envelope insertion station in the mail inserting system.
In a typical mail inserting system, a plurality of enclosure feeders are used to release enclosure documents onto a chassis or deck. The released documents are collated into stacks and pushed from an upstream direction to a downstream direction into an envelope inserting station where each stack of the collated documents is inserted into an envelope. Mail inserting systems are known in the art. For example, Roetter et al. (U.S. Pat. No. 4,169,341) discloses a mail inserting system consisting of a document collating section and an envelope insertion section, wherein a plurality of document feeders are used to release documents onto a continuous conveying mechanism that collects and collates the documents and then conveys the collated documents to the envelope insertion section in a continuous manner. Auerbach et al. (U.S. Pat. No. 5,660,030) discloses a high speed envelope inserting station wherein a plurality of depressor fingers are used for applying pressure to the envelope flap during the insertion of the enclosure material. At the same time, a pair of throat openers are used to keep the throat of the envelope opened by separating the bottom side of the envelope from the upper side. Belec et al. (U.S. Pat. No. 5,374,044) discloses an envelope inserting device wherein a plurality of rotatable stops are used to register the envelope at the insertion location. The rotatable stops can be rotated away to allow a stuffed envelope to move downstream. Before the envelope is stuffed, it is moved into the insertion location by a plurality of endless belts. After being stuffed, the envelope is moved away from the insertion station by the same belts. Furthermore, a rotatable vacuum drum and a fixed vacuum deck are used to provide a vacuum suction force to the envelope for urging the envelope to press against the endless belts.
In general, a mail inserting system 1, as shown in FIG. 1, comprises an envelope supply module 10, an envelope insertion station 20 and an enclosure material supply module 30. In the envelope supply module 10, an envelope feeder (not shown) is used to retrieve one envelope 12 at a time from a stack 13 and release the retrieved envelope to the envelope insertion station. The envelope 12, after being fed from below a transport module 50 through an exit path 22, is moved to an insertion location defined by a plurality of rotatable stops 82. The flap of the envelope 12 stays opened as the enclosure material 32 is moved from the enclosure supply module 30 into the envelope insertion station 20 to be inserted into the envelope 12. After the insertion, the rotatable stops 82 are rotated away so that the stuffed envelope 42 can be moved out of the envelope insertion station 20.
In Belec et al., the vacuum ports on the vacuum deck are distributed over a large area so that the vacuum suction force can be applied to a large envelope as well as a small envelope. On the one hand, when a small envelope is positioned at the insertion location, a considerable part of the vacuum suction force is wasted because the envelope only covers a small number of vacuum ports. On the other hand, when a large envelope is used, it covers a large number of vacuum ports. Consequently, the suction force exerting on the large envelope may be too large, rendering the moving of the envelope from the upstream end to the insertion location difficult.
FIGS. 2 to 5 are schematic representations of a prior art transport module 50, wherein a plurality of endless belts 58, driven by rollers 54, 56, are used to move an envelope from the upstream end to the downstream end along a direction 250. There is a gap 60 between a plurality of adjacent endless belts 58, running along the belts from the upstream end to the downstream end. A registration mechanism 80 having a plurality of rotatable stops 82 is used to stop the envelope at an insertion location 240 so that enclosure material can be inserted into the envelope. Each of the rotatable stops 82 protrudes above the surface of the endless belts 58 through the gap 60 into the moving path of the incoming envelope. As shown in FIG. 3, when the rotatable stops 82 are oriented at an upright position, the edge 84 of each rotatable stop 82 provides a registration point to the envelope to be inserted with enclosure material. After the envelope is inserted with enclosure material, the rotatable stops will be rotated in a clockwise direction by 90 degrees so as to allow the stuffed envelope to move out of the insertion location along the moving direction 250. As shown in FIG. 4, the envelope 12 has a leading edge 14, a trailing edge 16 and a flap 18 at the trailing edge. The leading edge 14 of the envelope 12 is stopped by the rotatable stops 82. In order to hold down the envelope 12 for insertion, a vacuum module 70 is used to provide a suction force on the envelope 12. As shown in FIGS. 2 and 3, the vacuum module 70 comprises a plurality of vacuum ports 72 along the gaps 60. The vacuum module 70 has two air outlets 74 from which the air in the vacuum module 70 is drawn in order to create a negative pressure in the vacuum module 70. When the vacuum ports 72 are covered by the envelope 12, the covered vacuum ports 72 provide a vacuum suction force 272 through the gaps 60 for urging the envelope 12 to press against the endless belts 58. In addition to holding down the envelope 12 during the envelope insertion process, the suction force 272 provided by the vacuum ports 72 is also necessary for the movement of the envelope 12 to the insertion location 240. It should be noted that that after an envelope is released by the envelope supply module 10 through the exit path 22 (FIG. 1), the transport module 50 must pick up the envelope 12 and move it toward the downstream end. As the suction force 272 exerted through the vacuum ports 72 causes the envelope 12 to press against the surface of the endless belts 58, frictional force between the envelope 12 and the surface of the endless belts 58 is developed, and this frictional force renders it possible for the endless belts 58 to carry the envelope 12 along the moving direction 250 until the leading edge 14 of the envelope 12 registers with the edge 84 of the rotatable stops 82 (see FIG. 3).
The envelope must be positioned at the insertion location in order to receive the enclosure material for insertion. To accommodate envelopes of different sizes, the position of the registration mechanism 80 must be adjustable so that the rotatable stops 82 can be moved toward the upstream end or toward the downstream end according to the size of the envelope. For registration purposes, the size of the envelope 12 is defined by the leading edge 14 and the trailing edge 16 of the envelope. To register a large envelope 12xe2x80x2, as shown in FIG. 5, the registration mechanism 80 is moved closer to the downstream end. A large envelope 12xe2x80x2 covers a large number of vacuum ports 72. While this coverage reduces the waste of the vacuum suction, it may create excessive frictional force between the envelope 12 and the surface of the endless belts 58 hindering the movement of the envelope 12xe2x80x2. In order to avoid this excessive frictional force problem, one could reduce the negative pressure in the vacuum module 70. However, the reduction of negative pressure may result in insufficient frictional force for a small envelope.
Thus, it is desirable and advantageous to provide a transport module wherein the vacuum suction force is more properly provided to the envelope at the insertion location, while the transport module can accommodate a wide range of envelope sizes.
It is a primary objective of the present invention to provide a transport module which is capable of providing a substantially equal vacuum suction force to envelopes of different sizes when the envelope is positioned at the insertion location. This objective can be achieved by disposing at least two vacuum modules in the transport module in order to provide the vacuum suction force to the envelope at the insertion location. One of the vacuum modules can be repositioned according to the size of the envelope.
Thus, according to the first aspect of the present invention, there is provided an envelope transport module to be used in an envelope insertion station of a mail inserting machine, wherein an envelope has a leading edge and a trailing edge defining a dimension of the envelope, the trailing edge having a flap which is opened for enclosure material insertion when the envelope is securely held at an insertion location in the envelope insertion station, wherein the transport module comprises:
a frame having an upstream end and a downstream end;
a transport mechanism disposed on the frame for moving the envelope from the upstream end to the insertion location, the transport mechanism having a support surface to support the envelope;
a registration mechanism to register the leading edge of the envelope as the envelope reaches the insertion location, wherein the registration mechanism is adjustably mounted on the frame so as to allow the registration mechanism to be positioned at a location between the upstream end and the downstream end in order to accommodate the dimension of the envelope; and
a vacuum suction device positioned relative to the frame between the upstream end and the downstream end so as to urge the envelope to press against the support surface, wherein
the vacuum suction device comprises a first vacuum module and a separate second vacuum module, and wherein
the first vacuum module is disposed between the upstream end and the registration mechanism near the upstream end to provide a suction force on the envelope near the trailing edge thereof, and
the second vacuum module is adjustably disposed between the first vacuum module and the registration mechanism so that the second vacuum module can be repositioned to provide a further suction force on the envelope near the leading edge thereof.
Preferably, the first vacuum module is fixedly disposed on the frame.
Preferably, the second vacuum module is mechanically linked to the registration mechanism so that the second vacuum module is relocated along with the registration mechanism, based on the dimension of the envelope.
Preferably, the transport mechanism comprises a plurality of conveyor belts moving from the upstream end to the downstream end, wherein a gap is provided between two adjacent conveyor belts, extending from the upstream end to the downstream end, and the second vacuum module has at least one vacuum port located in the gap for providing the further suction force.
Preferably, the registration mechanism comprises a plurality of rotatable stops operable
in a first position protruding over the support surface to register the leading edge of the envelope as the envelope is located at the insertion location, and
in a second position to retreat under the support surface so as to allow the envelope to move downstream after the insertion is completed.
According to the second aspect of the present invention, there is provided a method of securing an envelope on an envelope transport module in an envelope insertion station of a mail inserting machine, wherein the envelope has a leading edge and a trailing edge defining a dimension of the envelope, the trailing edge having a flap which is opened for enclosure material insertion when the envelope is securely held at an insertion location in the envelope insertion station, wherein the transport module comprises:
a frame having an upstream end and a downstream end;
a transport mechanism disposed on the frame for moving the envelope into the envelope insertion station from the upstream end to the insertion location, the transport mechanism having a support surface to support the envelope;
a registration mechanism to register the leading edge of the envelope as the envelope reaches the insertion location, wherein the registration mechanism is adjustably mounted on the frame so as to allow the registration mechanism to be located to a location between the upstream and downstream ends in order to accommodate the dimension of the envelope; and
a vacuum suction device positioned relative to the frame between the upstream end and the downstream end for urging the envelope to press against the support surface. The method comprises the steps of:
providing at least one first vacuum port in the vacuum suction device in order to apply a suction force on the envelope near the trailing edge thereof, and
providing at least one second vacuum port in the vacuum suction device between said at least one first vacuum port and the registration mechanism, wherein said at least one second vacuum port can be repositioned in order to apply a further suction force on the envelope near the leading edge thereof.
Preferably, said at least one vacuum port is mechanically linked to the registration mechanism so as to allow said at least one vacuum port to be repositioned along with the registration mechanism based on the dimension of the envelope.
The present invention will become apparent upon reading the description taken in conjunction with FIGS. 6 to 12.